Cell cycle-related variations in surface membrane components will be studied in T-cell lymphocytic cell lines (BW5147, WEHI 22.1), in a plasmacytoma (MDPC 315), and in normal or stimulated lymphocytes. They will include gp 70, an unidentified glycoprotein of 160-170,000 daltons molecular weight, surface immunoglobulin specific for DNP. An attempt will be made to relate cycle-determined expression to gene amplification, transcriptional and translational events, glycosylation of the protein product, membrane insertion, and "masking."